MOCVD growth of GaN on LiAlO2(100) substrates

GaN was grown on LiAlO2(100) using MOCVD with TMGa as Ga source, ammonia as N source, and H-2 as carrier gas. Because of the fairly good lattice match between LiAlO2 and GaN, a strong preferred GaN film with (1(1)overbar 00) orientation could be obtained on LiAlO2(100) even without using buffer layers which was very crucial to using Al2O3 as substrate. In the case without using low temperature buffer layers, high-quality GaN films can be obtained with FWHM of 530 arcsec, surface roughness of 20 nm (rms), mobility of 98 cm(2)/Vs, and carrier concentration of 3 x 10(18) cm(-3) at room temperature. The pretreatment of LiAlO2 substrates in ammonia played an important role in obtaining high-quality GaN. The possible effects of thermal expansion were also commented. Even though much information is still left unknown about GaN growth on LiAlO2 substrates, we can see that gamma-LiAlO2 single crystal is a promising substrate.